Hycanthone, lucanthone, niridazole, F30066 and some other antischistosomal nitrofurans are attracting wide concern because of their potential carcinogenic and mutagenic hazards to treated individuals in the human population. Our previous studies have shown that hycanthone, lucanthone and their indazole analogs are mutagenic in Neurospora crassa and these agents appear to induce predominantly multilocus deletion mutations. Our previous study also indicates that there is no correlation between mutagenicity and antischistosomal activity of hycanthone and its indazole analogs. It would be of interest to extend the studies on the mutagenic activity and the structure-function relationship of the other antischistosomal agents. The ad-3 test system of N. crassa is used in this study. Conidia from a genetically marked two-component heterokaryon are treated with antischistosomal agents. The treated and untreated conidia are analyzed for the presence of ad-3 mutants by the direct method. Based on the background counts and the number of mutants, the survival and the mutation frequency are determined. BIBLIOGRAPHIC REFERENCE: Ong, T., Callen, D. F., Huang, S., Batzinger, R. P., and Bueding, E.: Mutation induction by the antischistosomal drug F30066 in various test systems. Mutation Research 48:37-42, 1976.